WHEN CHANGING A TRACK ON THE DOZER, THE CHAIN HOOK SLIPPED OFF THE BOGIE. THE EMPLOYEE'S ARM WAS CAUGHT BETWEEN THE BOGIE AND THE TRACK. THIS RESULTED IN A SIGNIFICANT CONTUSION TO THE EMPLOYE E'S RIGHT FOREARM. THIS INJURY RESULTED IN RESTRICTED DUTY FOR THE EMPLOYEE. HOWEVER, EE WORKED 4 ON/4 OFF SHIFTS & 4 SHIFT CANCELLED. HE RETURNED NEXT SHIFT AT FULL CAPACITY.